1. Field of the Invention
The present invention relates to a method of manufacturing a nozzle plate, and more particularly, to a method of manufacturing a nozzle plate of which surface is covered with a liquid-repelling film on the liquid droplet ejection side.
2. Description of the Related Art
There are inkjet recording apparatuses, which form an image on a recording medium by ejecting ink droplets from nozzles formed on a print head, while moving the print head and the recording medium relatively with respect to each other. The print head has a nozzle plate formed with the nozzles (nozzle orifices) on a surface opposing the recording medium.
In the inkjet recording apparatus of this kind, it is known that, in order to stabilize the meniscus of the ink in the nozzle and to prevent adherence of ink droplets and soiling to the surface of the nozzle plate (ink droplet ejection surface), a liquid-repelling film is formed on the surface of the nozzle plate. In a method of manufacturing a nozzle plate of this kind, it is necessary to fill the nozzle orifices with resist.
For example, Japanese Patent Application Publication No. 09-076492 discloses a method of manufacturing a nozzle plate in which a dry film resist of an anticorrosive high polymer resin, such as a photosensitive film, is filled into the nozzle orifices formed in a nozzle forming substrate, whereupon the dry film resist is made to project by cutting the surface of the nozzle forming substrate by an etching process, and an ink-repelling surface treatment layer is then formed, whereupon the dry film resist is removed.
Japanese Patent Application Publication No. 2002-187267 discloses a method of manufacturing a nozzle plate in which a liquid-repelling film is formed on the whole surface of a nozzle forming substrate formed with nozzle orifices, whereupon a photosensitive dry film resist is applied onto the front surface of the nozzle forming substrate and onto the faces from the front surface to the positions where the meniscus is formed on the inner walls of the nozzle orifices, the unmasked liquid-repelling film is removed by etching, a liquid-philic film is formed onto the rear surface of the nozzle forming substrate and onto the inner walls of the nozzle orifices from which the liquid-repelling film has been removed, and the photosensitive dry film resist is then removed. According to this method, the liquid-repelling film is formed on the nozzle plate surface and the faces from the nozzle plate surface to the positions where the meniscus is formed on the inner walls of the nozzle orifices, whereas the liquid-philic film is formed on the rear surface of the nozzle plate and the faces from the rear surface to the positions where the meniscus is formed on the inner walls of the nozzle orifices.
In the present specification, the term “liquid-philic” means “having a strong affinity for the liquid (e.g., the ink)”. For example, in the case where the liquid or the ink is an aqueous solution or water-based, the term “liquid-philic” corresponds to “hydrophilic”. On the other hand, in the case where the liquid or the ink is an oleaginous solution or oil-based, the term “liquid-philic” corresponds to “oleophilic”.
However, if a resist is used as in the methods disclosed in Japanese Patent Application Publication Nos. 09-076492 and 2002-187267, then a problem arises in the stage of removing resist after forming the liquid-repelling film.
More specifically, in the case of a wet method which dissolves the resist by means of a solvent, such as an organic solvent, sulfuric acid and hydrogen peroxide, or the like, it is necessary to form a liquid-repelling film having resistance to organic chemicals, and this method is undesirable from the viewpoint of environmental safety. Furthermore, in the case of a dry method which removes the resist by means of decomposition by burning by means of plasma, it is difficult to remove completely the resist inside the nozzle orifices and nozzle blockage may occur as a result of residual resist.